GitLab automatically runs git gc and git repack on repositories after Git pushes. If needed you can change how often this happens, or to turn it off, go to Admin area > Settings (/admin/application_settings).

The housekeeping function will run a repack or gc depending on the "Automatic Git repository housekeeping" settings configured in Admin area > Settings

For example in the following scenario a git repack -d will be executed:

Project: pushes since gc counter (pushes_since_gc) = 10

Git GC period = 200

Full repack period = 50

When the pushes_since_gc value is 50 a repack -A -d --pack-kept-objects will run, similarly when the pushes_since_gc value is 200 a git gc will be run.

git gc (man page) runs a number of housekeeping tasks, such as compressing filerevisions (to reduce disk space and increase performance) and removing unreachable objects which may have been created from prior invocations of git add.